Apparatus for producing grids of storage batteries

ABSTRACT

AN APPARATUS FOR PRODUCING GRIDS OF STORAGE BATTERIES, WHEREIN A ROTARY MOLD, HAVING GRID CASTING GROOVES FORMED IN THE PERIPHERAL SURFACE THEREOF, AND A STATIONARY MOLD ARE ARRANGED IN CONFRONTING RELATION TO EACH OTHER AND MOLTEN LEAD OR A MOLTEN LEAD ALLOY IS POURED INTO A GAP DEFINED BETWEEN SAID MOLDS, WHEREBY DEFECT-FREE, THIN, EXCELLENT GRIDS ARE OBTAINED.   D R A W I N G

United States Patent inventors Shinya Yamauchi Osaka; Minoru Morita,Toyonaka-shi, Japan Appl. No. 769,266 Filed Oct. 21, 1968 Patented June28, 1971 Assignee Matsushita Electric Industrial Co., Ltd.

Osaka, Japan Priority Oct. 25, 1967, Sept. 25, 1968 Japan 68486/67,69487/67, 70658/68 and 70657/68 APPARATUS FOR PRODUCING GRIDS OF STORAGEBATTERIES 8 Claims, 16 Drawing Figs.

U.S. Cl 164/276, 164/88, 164/69, 164/283, 164/338, 164/348, 164/Dig.lInt. Cl B22d 11/06 Field of Search 164/88, 276

(Foreign & US), 278, 87, 281, 69, 70, (Battery Digest), 279, 283 (US)[56] References Cited UNITED STATES PATENTS 521,791 6/1894 Griscom207/11 1,651,678 12/1927 Davis 164/283X 2,714,235 8/1955 Brennan 164/702,745,151 5/1956 Brennan l64/276X 2,787,816 4/1957 Brennan 164/278X326,147 9/1885 Pielsticker et al. 164/276 Primary Examiner-J. SpencerOverholser Assistant Examiner-Vernon K. Rising Attorney- Stevens, Davis,Miller and Mosher ABSTRACT: An apparatus for producing grids of storagebatteries, wherein a rotary mold, having grid casting grooves formed inthe peripheral surface thereof, and a stationary mold are arranged inconfronting relation to each other and molten lead or a molten leadalloy is poured into a gap defined between said molds, wherebydefect-free, thin, excellent grids are obtained.

APPARATUS r011 rnonucmo cams or STORAGE BATTERIES This invention relatestoan apparatus for producing grids of storage batteries, and moreparticularly to such an apparatus which is adapted to produce thin,defect-free, excellent grids in a large quantity.

An object of the present invention is to provide an apparatus forcontinuously producing thin, defect-free, excellent grids, comprising arotary mold having a grid-molding groove formed in the peripheralsurface thereof and a stationary mold located in confronting relation tosaid rotary mold so as to define a grid-molding cavity therebetween intowhich molten lead or a molten lead alloy is poured.

Another object of the invention is to provide an apparatus of thecharacter described above, wherein a pouring basin is formed in thestationary mold in communication with an outlet for storing the moltenlead or molten lead alloy and a damper is provided in said pouring basinto regulate the quantity and pressure of the molten lead or moltenleadalloy being poured into the grid-molding cavity.

Still another object of the invention is to provide an apparatus of thecharacter described above, wherein said rotary mold and said stationarymold are connected with each other at their centers by a pair of armsand said stationary mold is provided with means for adjusting the angleof inclination thereof and elastic means for urging said stationary moldagainst said rotary mold; whereby variations in the space intervalbetween said rotary mold and said stationary mold, caused by thepressure of the molten lead or molten lead alloy poured into thegrid-molding cavity, are prevented.

Still another object of the invention is to provide an apparatus of thecharacter described above, wherein heating means is provided to melt andremove thin films of lead and lead alloy when such thin films are formedin the spacings defined by the beams of the molded grid.

Still another object of the invention is to provide an apparatus of thecharacter described above, wherein means is provided for cooling slowlythe grid molded in the molding cavity in the rotary mold so as to enablea grid of uniform structure to be obtained.

Grids of storage batteries have generally be produced by a methodwherein molten lead or molten lead alloy is poured into a molding cavitydefined by a pair of openable planary casting molds. However, because ofthe fact that the grid has complicated structure comprising a number oflongitudinally and laterally extending beams crossing each other, asshown in FIGS. and 16, and its size becomes large particularly when thethickness thereof, i.e. the thickness indicated by t in FIG. 16, isextremely small, eg 1 mm. or smaller, much difficulty has beenencountered in the casting operation due to unsatisfactory flow of themolten lead or molten lead alloy, and even when the casting operation isaccomplished satisfactorily, the grid molded has frequently had portionsof the beams thereof missing. Thus, it has been difficult to produce anexcellent grid by casting at high efficiency. On the other hand, storagebatteries are desired to have better discharge characteristics from thestandpoint of practical use and to meet such desire, there has been anincreasing demand for thin grids.

The apparatus of the present invention is so designed that grids, whichare sufficiently satisfactory to meet the aforesaid desire, can beproduced continuously in large quantities.

The present invention will be described in detail hereinafter withreference to the accompanying drawings, which illustrate the inventionby way of embodiment and in which:

FIG. 1 is a side elevational view showing an embodiment of an apparatusfor producing grids of storage batteries according to the presentinvention;

FIG. 2 is a fragmentary side elevational view, partially in section, ofa portion of the apparatus shown in FIG. 1;

FIG. 3 is a back elevational view showing means for retaining thestationary mold;

FIG. 4 is an illustrative view for explaining the pressure engagementbetween the rotary mold and the stationary mold;

FIG. 5 is a vertical sectional view showing the manner in which a gridis produced by casting;

FIG. 6 is a sectional view taken on the line VI-VI' of FIG. 5;

FIG. 7 is a vertical sectional view showing the manner in which a gridis produced by another embodiment of the apparatus of this invention;

FIG. 8 is a fragmentary top plan view showing the peripheral surface ofthe rotary mold;

FIG. 9 is a sectional view taken on the line IX-IX' of FIG. 8;

FIG. 10 is a side elevationalview of another form of the heating meansfor melting thin films of molten metal formed in the spacings defined bythe grid beams;

FIG. 11 is a front elevational view, partially in section, of theheating means shown in FIG. 10;

FIG. 12 is a diagram showing the electric circuit of the heating rollersof the heating means shown in FIG. 10;

FIG. 13 is a diagram showing the electric circuit of the temperaturedetecting roller of the heating means;

FIG. 14 is a fragmentary sectional view of an incomplete grid, with thinfilms of lead or lead alloy formed in the spacings defined by the gridbeams;

FIG. 15 is a top plan view ofa completed grid after the thin films havebeen melted away; and 7 FIG. 16 is a sectional view taken on the lineXVI-XVI of FIG. 15.

Referring to the drawings, reference numeral 1 designates a stationarymold which has a pouring basin 3 formed therein in communication with amolten metal outlet 2. The stationary mold l is provided with a damper 7to regulate the flow rate of a molten metal 5, i.e. molten lead ormolten lead alloy, which is supplied into the pouring basin 3 through asupply tube 4. In the bottom wall of the pouring basin 3 is provided aheating tube 8 so as to prevent the molten metal 5 from solidifying insaid pouring basin, while in the lower portion of the inside of a curvedsurface 11, confronting the rotary mold 10, is arranged a cooling tube13 for circulating tepid water or the like therethrough, for therebysolidifying the molten metal 5 being poured from the outlet 2 intogrid-molding grooves 12 formed in the peripheral surface of a rotarymold 10. The cooling tube 13 and the heating tube 8 are thermallyisolated from each other by means of a heat insulation plate 14 embeddedtherebetween.

On the other hand, the rotary mold 10, as shown in FIGS. 1, 2 and 5, isformed into the shape of a drum and the gridshaped grooves 12 are formedin the peripheral surface thereof so as to define peripheral edges 15 asbest shown in FIG. 8. As seen in FIG. .6, the rotary mold 10 engages thestationary mold 1 in confronting relation, defining a grid-moldingcavity 12.

The stationary mold l and the rotary mold 10 are coupled by means of apair of arms 19 each of which has one end pivotally connected to abearing at the center of the rotary mold l0 and the other end to thecenter of the sidewall of the stationary mold 1 as shown in FIGS. 1 and2. The stationary mold l is supported on a supporting frame 20 by fourangle of inclination adjusting bolts 21 and four squarely arrangedsprings 22 engaging the back surface of said stationary mold, in such amanner as to hold said stationary mold in contact with the peripheralsurface of the rotary mold 10. Each arm 19 is provided at the centralportion thereof with a threaded rod 23 for adjusting the length of saidarm. Namely, the length of the arm 19 is optionally adjusted by screwthreading the threaded rod 23 into or from the arm.

The stationary mold I is connected to each one of the pair of arms 19 bya bolt 25, provided at the center of each side surface thereof, whichextends through a slot 24 formed at one end of each arm 19 and issecured in position by a spring 27 which is pressed at one end by anadjusting screw 26.

Reference numeral 28 designates four bolts threadably extending throughan upright wall 29, integral with the frame 20, to press and hold foursprings 22 respectively which have one ends thereof received in holes 30formed in the back surface of the stationary mold l. The rotary mold 10is supported by wedge-shaped frames 31. The stationary mold l and therotary mold 10 may be fixed in positions, with a predetermined gap,necessary for the casing of a grid, formed therebetween in the followingmanner:

First of all, the springs 27 disposed in the slots 24 of the respectivearms 19 and the four springs 22 biasing the back surface of thestationary mold 1 are released and then the lengths of the arms 19 areadjusted by screw threading the adjusting threaded rods 23 into therespective arms. After a gap required for the casing of the grid hasbeen secured between both molds l and 10, the threaded rods 23 are fixedin their positions and the four bolts 21 are also fixed by means of locknuts 32.

Then, the adjusting screw 26, having its free end projecting into theslot 24 of each arm 19, is screw threaded against the force of thespring 27 thereby to impart an elastic force to said spring andsimultaneously the four bolts 28 are screw threaded through the uprightwall 29 of the frame 20 to press the respective springs 22 which in turnwill urge the stationary mold 1 toward the rotary mold 10 from the backside thereof. The bolts 28 are fixed in position by respective lock nut33.

The biasing forces of the springs 27 and 22 are preferably such that thegap required for the casing of a grid therein can be maintainedconstantly even when the pressure of a riser head, etc. acting betweenthe stationary mold 1 and the rotary mold 10 becomes large duringoperation of the apparatus. In this case, unnecessarily large biasingforces of these springs must be avoided because if the biasing forcesare excessively large, the frictional resistance between the stationarymold I and the rotary mold 10 increases, with the result that aprescribed rate of rotation of the rotary mold 10 cannot be maintainedand both molds will undergo wear.

As shown in FIG. 4, the stationary mold l is urged against the rotarymold 10 by the elastic force F of springs 27 acting on the bolts 25, acounterclockwise moment M developed by the upper two ones of foursprings 22 urging the back surface of the stationary mold l and aclockwise moment M developed by the lower two ones of said springs. Theupper two springs 22 and the lower two springs 22 are located such thatthe extensions of their axes pass above and below the bolts 25 on thesidewalls of the stationary mold 1 respectively. Normally, the moment Mis made greater than the moment M because the thickness of the grid tobe produced is deter mined by the spacing between the lower end of thecurved surface 11 of the stationary mold 1 and the rotary mold 10.

Description has been made hereinabove with reference to the case whenthe pressure acting between the molds 1 and 10 during pouring ofa moltenmetal into the molding'cavity 12 is large. When the riser head is small,the biasing force F of the springs 27 is not necessarily required andthe arms 19 may be connected directly to the bolts on the sidewalls ofthe stationary mold l at one end thereof.

Reference numeral 34 designates a heating belt provided beneath thestationary mold l in such a manner as to contact the grooved portion 12on the peripheral surface of the rotary mold 10. The heating belt 34 isformed out of an endless stainless steel plate or the like and trailedaround two driving drums 35, 36 to be driven thereby in the direction ofarrow A while being heated to elevated temperature by heating tubes 37,38 arranged inside and outside of the loop of belt respectively. Asupport roller 39 is provided at the bottom of the rotary mold 10 forrotation in the direction of arrow B.

Between the supporting roller 39 and the rotary mold I is provided aknife-shaped separator 40 which has a sharp edge and by which a web ofsolidified lattice mold being delivered continuously in contact with theperipheral surface of the rotary mold is separated therefrom. The web ofgrid 42 of lead or lead alloy, having been separated from the rotarymold 10, is sent'forwardly of the molding apparatus by means of a pairof pinch rollers 41 which are positioned one on each side of the grid 42and rotating in opposite directions to each other as indicated by arrowC.

A cooling tube 43 provided exterior of the rotary mold 10, from whichtepid water or the like is sprayed to prevent excessive heating of therotary mold, while heating tube 43' is provided to preheat theperipheral surface of the rotary mold.

Next, the operation of the apparatus, constructed as described above,for the production of a grid of the type shown in FIG. 15, will beexplained hereunder.

First of all, a gap necessary for the casing of the grid 44 is definedbetween the stationary mold 1 and the rotary mold 10 to be rotated inthe direction of arrow D, and then the stationary mold 1 is urged towardthe rotary mold 10 by the springs 27 and 22. Molten lead or molten leadalloy 5 is introduced into the pouring basin 3 through the molten metalsupply tube 4 and the damper 7 is moved vertically to regulate the flowrate and the pressure at which the molten metal 5 is poured. The moltenmetal 5 is poured into the molding cavity 12 formed in the peripheralsurface of the rotary mold 10 through the inlet 2 with no head. In thepouring basin 3, the molten metal 5 is not solidified and has a suitablefluidity by virtue of the heat from the heating tube 8, but when pouredinto the molding cavity in the peripheral surface of the rotary mold 10it begins to solidify by being cooled by said cold rotary mold. The grid42 thus molded has its thickness adjusted during its passage throughbetween the rotary mold l0 and the lower edge of the curved portion 11of stationary mold 1. In this case, the grid is also cooled from thesurface by the cooling tube 13 provided interior of the curved portion11. The web of continuous grid 42 thus molded in the molding cavity 12in the peripheral surface of the rotary mold is subjected to a spray oftepid water or the like from the cooling tube 43, whereby it is furthercooled without undergoing an abrupt structural change.

As stated previously and shown in FIG. 6, the rotary mold 10 and thestationary mold 1 form therebetween under the biasing forces of thesprings 27 and 22 only that amount of a gap which is needed for thecasting of the grid. In practice, however, a thin film oflead or leadalloy is formed on the surface of the grid 42, particularly in the spacedefined by the grid beams 54, integrally therewith on account of apressure, such as the riser head of the molten metal 5, and theextremely high fluidity of said molten metal. Such thin film 46 ismelted away by the heat of the heating belt 34 when the surface of thegrid 42 is brought into contact therewith. The heating belt 34 can beused continuously repeatedly because the lead attached thereto iscleared therefrom during its rotation.

The grid 42 having the thin film 46 eliminated therefrom in the mannerdescribed is further carried on the rotary mold 10 while being attachedto the peripheral surface thereof, and reaches the bottom portion ofsaid rotary mold where the supporting roller 39 is provided. At thisportion, the knife-shaped separator 40 is inserted between the grid 42and the rotary mold 10, so that the grid 42 is separated from the rotarymold l0 and delivered by the pinch rollers 41 in a directiontangentially of said rotary mold.

The web of grid thus obtained may be cut into a suitable length at apoint past the pinch rollers 41, whereby a piece of grid 44 is obtainedas shown in FIG. 15. Thereafter, the grid 44 is filled with an activesubstance and subjected to a suitable chemical treatment, to be used asan electrode plate. Alternatively, the web of grid may be cut into asuitable length after it is filled with the paste and subjected to thechemical treatment.

Beside the foregoing, the present inventors have confirmed through manyexperiments that the grid 44 as shown in FIG. 15 may also be produced ina large quantity by a simple apparatus as shown in FIG. 7.

In the apparatus shown in FIG. 7, an arcuate stationary mold l is heldopposite to the rotary mold 10, having the gridmolding cavity formed inthe peripheral surface thereof, by means of springs as those mentionedin the preceding embodiment or by an elastic mechanism making use ofpneumatic or hydraulic pressure, with only that much of gap therebetweenwhich is needed for the formation of the grid 44, and molten lead ormolten lead alloy is poured into said gap directly from the molten metalsupply tube 4 in an amount sufficient to form the grid 44.

In this case, since the molten metal 5 is supplied through the supplytube 4 in an amount just sufficient for the formation of the grid 44 andnot in excess thereto, the molten metal can be poured into the moldingcavity in the peripheral surface of the rotary mold 10, with no portionthereof flowing down through between said rotary mold and the lower edgeof stationary mold 1', even though a pouring basin or a flow rateregulating damper is not provided in the stationary mold.

The stationary mold 1' preferably has a heating tube or other headingmeans embedded in the upper portion thereof so as to prevent rapidcooling and solidification of the molten metal poured, and has a coolingtube or other cooling means embedded in the lower portion thereof tosolidify the molten metal. The molten metal 5 poured into the gapbetween the rotary mold l0, rotating in the direction of arrow D, andthe stationary mold l, is cooled and solidified slowly, and is subjectedto a spray of tepid water or the like from the cooling tube 43 at alower point past the stationary mold 1', whereby the solidification ofmolten metal is further promoted. The web of grid thus formed isseparated from the rotary mold by the separator at the position of thesupporting roller 39 an sent into the pinch roller 41. By cutting theweb of grid 42 into a predetermined length, a grid unit 44 as shown inFIG. 15 is obtained.

In this case also, a thin film 46 or lead or lead alloy is formed overthe grid beams 45 in the stage of formation of the web of grid.Therefore, it is necessary to provide the heating belt 34 to eliminatethe thin film as in the preceding embodiment.

The depth of the molding grooves 12, particularly the grooves 18, formedin the peripheral surface of the rotary mold 10 must be determined inaccordance with the desired thickness of grid since the thickness 1 ofthe grid web 42 or the grid 44 depends upon such depth.

It is of course possible to cast continuously grids of thickness rangingfrom large thickness to very thin thickness by the selective use ofrotary molds having varying depth of the grooves 12, particularly thegrooves 18, but the present invention is highly variable in that gridsof particularly small thickness, that is, a thickness of 1 mm. orsmaller, can be formed satisfactorily with no portions of the beamsmissing.

Although in the embodiments described above, use is made, for melting ohthe thin film 46 formed over the mesh of the grid 44, of heating meanswhich comprises an endless stainless steel plate engaged around twodriving drums to be rotated thereby in contact with the web of grid 42,one shown in FIGS. 10 and 11 may also be used.

Namely, referring to FIGS. 10 and 11, a driving roller 47 mounted on arotary shaft 49 is rotatably supported by a pair of bearings 48, 48 andone end of the rotary shaft 49 is extended outwardly through one of thebearings 48' with the driving chain gearing 50 mounted thereon. Thebearings 48, 48 are supported on a vertical, inverted U-shaped arm 51.The arm 51 is provided at the central portion thereof with a cylindricalmember 52 in which is received a supporting column 58 with a spring 57disposed in a cavity 56 in the lower end thereof. The supporting column52 is rotatably mounted on a bearing member which supports a heatingroller 53 and a temperature detecting roller 54. A supporting rod 59extends through upright portions 60, 60' of the bearing member 55 andalso through the top end of the supporting column 58. The bottom plate61 of the bearing member 55 has an opening 62 formed in the centerthereof to provided for rotation of the supporting column 58.

The heating roller 53 is rotatably mounted on one end ofthe uprightportions 60, 60' of bearing member 55, while the temperature detectingroller 54 is rotatably mounted on hearing blocks which are slidablydisposed in slots 63 formed in the walls of the upright portions 60, 60'respectively while being biased by springs 64.

The endless heating belt 34 of stainless steel plate is engaged aroundthe three rollers, i.e. the driving roller 47, the heating roller 53 andthe temperature detecting roller 54, and held in contact with thegrooved portion 12 of the peripheral surface of rotary mold 10 at aportion between the heating roller 53 and the temperature detectingroller 54 under the biasing force of the spring 57. These rollers 47, 53and 54 rotate in the direction of arrow E to drive the belt 34 at thesame speed as the peripheral speed of the rotary mold 10. Referencenumeral 66 designates a heating tube to heat the belt 34 before theheating roller 53 and 67 designates a wire brush to remove lead or leadalloy from the belt 34 which is attached to said belt upon melting.

The heating roller 53 has a plurality of rod-shaped heaters 68 embeddedtherein at the same circular pitch and these heaters are connected to apower source through slip rings 70 and a brush 71, mounted on an end ofa rotary shaft 69, as shown in FIG. 12. A current conducted through therodshaped heaters 68 from the power source is controlled by atemperature switch 74 which is connected to a thermocouple 72 along witha thermoelectric thermometer 73, and thermocouple 72 being disposedwithin the temperature detecting roller 54 for detecting the temperatureof the belt 34 as shown in FIG. 13. Namely, the temperature switchoperates in such a manner that the current passing through therod-shaped heaters 68 in the heating roller 53 in interrupted when thewhen the temperature detected by the thermocouple 72 is higher than apredetermined value,while the current is conducted through therod-shaped heaters 68 to heat the roller 53 when said temperature islower than the predetermined value, thereby heating the heating belt 34to the predetermined temperature.

Thus, the heating belt 34 is maintained in a certain temperature rangein the proximity of the predetermined temperature. Reference numeral 75designates slip rings electrically connected to the thermocouple 72, 76a brush and 77 a rotary shaft of the temperature detecting roller.

It is to be understood that the positions of the heating roller 53 andthe temperature detecting roller 54 may be changed with each other asdesired. It is also to be understood that where the quantity of heatrequired for heating the belt 34 is relatively small, a single rollermay be used with the heaters and the temperature detecting meansdisposed therein or further a roller having the heaters and thetemperature detecting means mounted therein may be contacted directlywith the grooved portion 12 of the rotary mold 10, without using thebelt 34.

The temperature to which the heating belt 34 is heated for themelt-removing the thin film 46 formed over the mesh of grid web 42 isvariable depending upon whether the molten metal 5 consists of lead onlyor a lead alloy. In the case, for example, of a lead-antimony alloycontaining 5 percent of antimony, the heating belt 34 is preferablymaintained in the temperature range from 295 C. to about 320 C. as themelting point of said alloy is 295 C. Overheating of the heating beltwill provide the danger of the grid beams 45 being melted. It will beappreciated, therefore, that the temperature detecting means in thetemperature detecting roller 54 is set such that the rod-shaped heaters68 in the heating roller 53 are deenergized when the temperature of theheating belt detected has reached 320 C. and are energized when saidtemperature has dropped to a level immediately above 295 C.

On the other hand, when the molten metal 5 consists solely of lead, theheating belt 43 is preferably maintained in the temperature range fromabout 327 C. to about 340 C. for the same reason as mentioned above, inconsideration of the fact that the melting point of pure lead is 327.4C.

Upon melt-removing the thin film 46 from the web of grid 42 by theheated belt 34 in the manner described, the resultant molten lead orlead alloy is attached to the belt. However, the molten lead or leadalloy is brushed off the belt by the wire brush 67 so that the belt maybe used continuously.

As will be understood from the foregoing description, it is possibleaccording to the present invention to produce excellent, defectnfree,thin grid in'a large quantity by pouring molten lead or molten leadalloy into the gap formed between the rotary mold, having agrid moldinggrooves formed in the peripheral surface thereof, and the stationarymold located in confronting relation to said rotary mold.

We claim:

1. An apparatus for producing grids for storage batteries, comprising arotary mold part provided with gridlike grooves in the peripheralsurface. thereof, a stationary mold disposed in confronting relationshipto the peripheral surface of said rotary mold part to cooperate withsaid gridlike grooves to define therebetween a grid casting cavity, saidstationary mold part comprising a molten metal outlet positioned inopposite relationship to said gridlike grooves in the periphery of saidrotary mold part, a reservoir for a molten metal in communication withsaid molten metal outlet, a stopper movable up and down for regulatingthe flow rate and the pressure of said molten metal contained in saidreservoir, heating tubes adjacent the bottom of said reservoir forcirculating a heating medium therethrough, cooling tubes adjacent saidcurved concave surface for circulating a coolant therethrough, and aheat insulating plate thermally separating said heating tubes apart fromsaid cooling tubes.

2. An apparatus according to claim 1 further comprising a pair of armsfor interconnecting said rotary and stationary mold parts substantiallyat their central points, means for resiliently urging said stationarymold part against said rotary mold part and leg members for adjustingthe inclination of said stationary mold part with respect to said rotarymold part.

3. An apparatus according to claim 1 further comprising means formelting off thin films of metal closing the openings of the mesh as saidgridlike cast is continuously delivered from said casting cavity, saidfilm being formed by the narrow gap defined between the confrontingperipheral surfaces of said stationary and rotary mold parts, saidmelting means comprising a heated endless belt movable in contact withthe peripheral surface of said rotary mold part at the portiondownstream of said stationary mold part, at least a pair of drums forsupporting said endless belt, at least one of said drums beingpower-driven to move .said endless belt, and means for heating saidendless belt.

4. An apparatus according to claim 3 in which said means for heatingsaid endless belt comprises heating tubes disposed adjacent the run ofsaid endless belt on opposite sides thereof.

5. An apparatus according to claim 3 in which said means for heatingsaid endless belt comprises heating tubes disposed adjacent the run ofsaid endless belt on the outer side thereof and heater means disposedwithin at least one of said drums.

6. An apparatus according to claim 5 further comprising a temperaturedetecting roller having a thermocouple disposed therein and mounted inrolling contact with said endless belt, at least one of said drumshaving heater means disposed therein and means responsive to saidthermocouple for controlling said heaters.

7. An apparatus according to claim 1 in which said coolant is tepidwater for slowly cooling the cast metal within said grid casting cavity.

8. An apparatus according to claim 1 in which said molten metal isselected from a group including lead and lead alloys.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 587,717 Dated June 28, 1971 Inventor(s) Shinya YAMAUCHI et al It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

The first Japanese application number should read -6 9 486/67-- and not"6g486/6'7 Signed and sealed this 11th day of January 1972.

(SEAL) Attest:

EDWARD M.FLETGHER,JR. ROBERT GO'I'TSCHALK Attesting Officer ActingCommissioner of Patents FORM P0405) "069) uscoMM-Dc wave-P09 3 U 5GOVERNMENY PRINTI'; OFFICE 9Q, 0-165-334

